Some points to consider:
DNR is in direct competition with the game/hunting facilities. DNR receives money from people hunting on DNR managed land (this includes private land under a DNR agreement). On many private game ranches, hunting licenses (DNR money) are not required.
MI senators who support the DNR hog ban have largely cited industry protection reasons, not environmental protections. The MI commercial pork industry strongly supports this ban:
Pseudorabies is one reason cited by the industry for not wanting feral pigs around (the cite I am about to link contrasts with other reports that 20 percent or less of feral hogs are infected/carriers). I can see why it would be a concern given what conditions leave animals open to infection:
It says that stress from overcrowding and poor nutrition can increase exposure rates.
More on Industry concerns:
Killing fenced, contained pigs will not help the issue, and that is just one area the ban oversteps on. The vague language and lack of scientific distinguishing characteristics is yet another concern:
According to the recommendation from the Natural Resources Commission and the Agriculture Commission, the MDA and DNR should "pursue the following recommendations:
• Ban all recreational shooting of swine behind fences;
• depopulate swine from all Michigan privately owned cervid ranches, game ranches, wild game breeding facilities and other enclosed ranches;
Total hippie tree-hugged here who hates canned hunts....but, I appreciate fairness and solutions that work for the environment regardless of my personal feelings. I don't see this ban as helping the environment. Solid management, regulation, monetary incentives, and working with people will help with the feral hogs. Having farmers send in photos so an unqualified official can tell them if their fenced in hog is "feral" or not..I'm definitely skeptical.